Impeoved



@einen tates rttrntA @time HIRAM B. NiCKERSON, OF BOSTON, MASSACHUSETTS, ASSlGNOR TO HIM- SELF AND S'llLLMAN B. ALLEN, OF SAME PLACE.

Lette-rs .Paten-t No. 75,568, dated fifarch i7, 1868.

IMPBQVED FILE.

TO ALL PERSONS TO WHOM THESE PRESENTS SHALL COME: t

Be it known that I, Hman B. NICKERSON, of Boston, in the county oi` Sutoih, and State of Massachusetts, have made a new and useful invention, having reference to Rusps and do hereby declare the same to he fully described in. the following specification, and represented in Figures 'l and 3o? the accompanying drawings, which exhibit the arrangement of the rasp-tecth constituting my invention or improvement. Figure 2 exhibits the common arrangement of such teeth.

In the ordinary Way of cutting the teeth of a resp, the tool or cutter is held nt nn acute angle with the surface on which the tooth is to be raised,` and it is ranged in a direction lengthwise of the rasp, so as to make the cut in that direction, in which case the cutting front face oi"a tooth usually stands at or very nearly at right angles with the opposite edges ofthe rnsp-blank.

In carrying out my improvement, the teeth of each range are to be cut so that their fronts or cutting-faces shall he oblique, or at acute angles with the edges of the rnsp, those of' one range being,r made to stand obliquely in one direction, while those of the next range are made to stand ohliquely in the opposite direction, as shown in fg.1. The singles of Obliquity of the cutting-faces of the teeth, I prefer to have forty-tive degrees, or thereabouts, with the edges of the rasp, the same being as shown in fig. 1, in which the teeth of one range are represented at aa, and those of the next rangek at b b. uThe edges of the rasp are shown at c c.

With my improved or oblique arrangement of each tooth, it is caused, when in use, to cut with a drawing stroke, and to operate so much better than the square tooth, or that arranged as shown in fig. 2, (viz, at right angles to the edges of the rasp,) that a rasp made in my improved manner will out through a bar of wood in about one-third the time that would he required to accomplish the sume with a square-tooth rasp.

An experiment made with one of my improved rnsps and another of the ordinary kind, of the size, demonstrated that it required hut thirty-seven movements of my rasp to ninety-two of the common rnsp, to effect like cuts through a bar of wood.

My improved rasp works much more easily than thc common rasp, and in other respects to better advantage. Its teeth do not choke, but readily clear themselves of the wood or raspings. i

I claim a rasp having the teeth of euch range of teeth disposed ohliquely to the edges of the rasp, and so that the cutting-face of each tooth shall have its Obliquity arranged in a direction opposite to or about at right angles with that of each of the teeth oi' the next adjacent range, the whole being substantially as exhibited in iig. 1, and as hereinbefore described.

HIRAM B. NIGKERSON.

Witnesses:

R. H. EDDY, F. P. HALE, Jr. 

